In a Classical Genetic Experiment,Newcombe Spread E

question 52

Multiple Choice

In a classical genetic experiment,Newcombe spread E.coli cells on complete medium.After several generations of growth,he replica-plated the colonies onto two plates with complete medium plus a selective agent.Colonies on the first replica were left untouched,while on the second replica,they were respread,allowing bacteria from each colony to be "moved" to a new location on the plate.Significantly more mutants after spreading (resistant to the selective agent) were observed than if they had not been respread.The experiment was used to:

• A)demonstrate how to screen for environmental mutagens.
• B)demonstrate that in some cases mutations are caused by the selective agent itself.
• C)provide evidence that mutations occur in the absence of the selective agent.
• D)provide evidence that mutation occurs in prokaryotes as well as in eukaryotes.
• E)show a direct correlation between the amount of the selective agent used and the number of resistant mutants.

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